/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 * Created by Arjan van de Ven <arjanv@redhat.com>
 *
 * Copyright (C) 2004 Ferenc Havasi <havasi@inf.u-szeged.hu>,
 *                    University of Szeged, Hungary
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: compr.c,v 1.45 2005/07/26 13:24:40 havasi Exp $
 *
 */

#include "compr.h"

static DEFINE_SPINLOCK(jffs2_compressor_list_lock);

/* Available compressors are on this list */
static LIST_HEAD(jffs2_compressor_list);

/* Actual compression mode */
static int jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;

/* Statistics for blocks stored without compression */
static uint32_t none_stat_compr_blocks = 0, none_stat_decompr_blocks = 0, none_stat_compr_size = 0;

/* jffs2_compress:
 * @data: Pointer to uncompressed data
 * @cdata: Pointer to returned pointer to buffer for compressed data
 * @datalen: On entry, holds the amount of data available for compression.
 *	On exit, expected to hold the amount of data actually compressed.
 * @cdatalen: On entry, holds the amount of space available for compressed
 *	data. On exit, expected to hold the actual size of the compressed
 *	data.
 *
 * Returns: Lower byte to be stored with data indicating compression type used.
 * Zero is used to show that the data could not be compressed - the
 * compressed version was actually larger than the original.
 * Upper byte will be used later. (soon)
 *
 * If the cdata buffer isn't large enough to hold all the uncompressed data,
 * jffs2_compress should compress as much as will fit, and should set
 * *datalen accordingly to show the amount of data which were compressed.
 */
uint16_t jffs2_compress(struct jffs2_sb_info* c, struct jffs2_inode_info* f,
                        unsigned char* data_in, unsigned char** cpage_out,
                        uint32_t* datalen, uint32_t* cdatalen)
{
	int ret = JFFS2_COMPR_NONE;
	int compr_ret;
	struct jffs2_compressor* this, *best = NULL;
	unsigned char* output_buf = NULL, *tmp_buf;
	uint32_t orig_slen, orig_dlen;
	uint32_t best_slen = 0, best_dlen = 0;

	switch(jffs2_compression_mode) {
		case JFFS2_COMPR_MODE_NONE:
			break;

		case JFFS2_COMPR_MODE_PRIORITY:
			output_buf = kmalloc(*cdatalen, GFP_KERNEL);

			if(!output_buf) {
				printk(KERN_WARNING "JFFS2: No memory for compressor allocation. Compression failed.\n");
				goto out;
			}

			orig_slen = *datalen;
			orig_dlen = *cdatalen;
			spin_lock(&jffs2_compressor_list_lock);
			list_for_each_entry(this, &jffs2_compressor_list, list) {
				/* Skip decompress-only backwards-compatibility and disabled modules */
				if((!this->compress) || (this->disabled))
					continue;

				this->usecount++;
				spin_unlock(&jffs2_compressor_list_lock);
				*datalen  = orig_slen;
				*cdatalen = orig_dlen;
				compr_ret = this->compress(data_in, output_buf, datalen, cdatalen, NULL);
				spin_lock(&jffs2_compressor_list_lock);
				this->usecount--;

				if(!compr_ret) {
					ret = this->compr;
					this->stat_compr_blocks++;
					this->stat_compr_orig_size += *datalen;
					this->stat_compr_new_size  += *cdatalen;
					break;
				}
			}
			spin_unlock(&jffs2_compressor_list_lock);

			if(ret == JFFS2_COMPR_NONE) kfree(output_buf);

			break;

		case JFFS2_COMPR_MODE_SIZE:
			orig_slen = *datalen;
			orig_dlen = *cdatalen;
			spin_lock(&jffs2_compressor_list_lock);
			list_for_each_entry(this, &jffs2_compressor_list, list) {
				/* Skip decompress-only backwards-compatibility and disabled modules */
				if((!this->compress) || (this->disabled))
					continue;

				/* Allocating memory for output buffer if necessary */
				if((this->compr_buf_size < orig_dlen) && (this->compr_buf)) {
					spin_unlock(&jffs2_compressor_list_lock);
					kfree(this->compr_buf);
					spin_lock(&jffs2_compressor_list_lock);
					this->compr_buf_size = 0;
					this->compr_buf = NULL;
				}

				if(!this->compr_buf) {
					spin_unlock(&jffs2_compressor_list_lock);
					tmp_buf = kmalloc(orig_dlen, GFP_KERNEL);
					spin_lock(&jffs2_compressor_list_lock);

					if(!tmp_buf) {
						printk(KERN_WARNING "JFFS2: No memory for compressor allocation. (%d bytes)\n", orig_dlen);
						continue;
					} else {
						this->compr_buf = tmp_buf;
						this->compr_buf_size = orig_dlen;
					}
				}

				this->usecount++;
				spin_unlock(&jffs2_compressor_list_lock);
				*datalen  = orig_slen;
				*cdatalen = orig_dlen;
				compr_ret = this->compress(data_in, this->compr_buf, datalen, cdatalen, NULL);
				spin_lock(&jffs2_compressor_list_lock);
				this->usecount--;

				if(!compr_ret) {
					if((!best_dlen) || (best_dlen > *cdatalen)) {
						best_dlen = *cdatalen;
						best_slen = *datalen;
						best = this;
					}
				}
			}

			if(best_dlen) {
				*cdatalen = best_dlen;
				*datalen  = best_slen;
				output_buf = best->compr_buf;
				best->compr_buf = NULL;
				best->compr_buf_size = 0;
				best->stat_compr_blocks++;
				best->stat_compr_orig_size += best_slen;
				best->stat_compr_new_size  += best_dlen;
				ret = best->compr;
			}

			spin_unlock(&jffs2_compressor_list_lock);
			break;

		default:
			printk(KERN_ERR "JFFS2: unknow compression mode.\n");
	}

out:

	if(ret == JFFS2_COMPR_NONE) {
		*cpage_out = data_in;
		*datalen = *cdatalen;
		none_stat_compr_blocks++;
		none_stat_compr_size += *datalen;
	} else {
		*cpage_out = output_buf;
	}

	return ret;
}

int jffs2_decompress(struct jffs2_sb_info* c, struct jffs2_inode_info* f,
                     uint16_t comprtype, unsigned char* cdata_in,
                     unsigned char* data_out, uint32_t cdatalen, uint32_t datalen)
{
	struct jffs2_compressor* this;
	int ret;

	/* Older code had a bug where it would write non-zero 'usercompr'
	   fields. Deal with it. */
	if((comprtype & 0xff) <= JFFS2_COMPR_ZLIB)
		comprtype &= 0xff;

	switch(comprtype & 0xff) {
		case JFFS2_COMPR_NONE:
			/* This should be special-cased elsewhere, but we might as well deal with it */
			memcpy(data_out, cdata_in, datalen);
			none_stat_decompr_blocks++;
			break;

		case JFFS2_COMPR_ZERO:
			memset(data_out, 0, datalen);
			break;

		default:
			spin_lock(&jffs2_compressor_list_lock);
			list_for_each_entry(this, &jffs2_compressor_list, list) {
				if(comprtype == this->compr) {
					this->usecount++;
					spin_unlock(&jffs2_compressor_list_lock);
					ret = this->decompress(cdata_in, data_out, cdatalen, datalen, NULL);
					spin_lock(&jffs2_compressor_list_lock);

					if(ret) {
						printk(KERN_WARNING "Decompressor \"%s\" returned %d\n", this->name, ret);
					} else {
						this->stat_decompr_blocks++;
					}

					this->usecount--;
					spin_unlock(&jffs2_compressor_list_lock);
					return ret;
				}
			}
			printk(KERN_WARNING "JFFS2 compression type 0x%02x not available.\n", comprtype);
			spin_unlock(&jffs2_compressor_list_lock);
			return -EIO;
	}

	return 0;
}

int jffs2_register_compressor(struct jffs2_compressor* comp)
{
	struct jffs2_compressor* this;

	if(!comp->name) {
		printk(KERN_WARNING "NULL compressor name at registering JFFS2 compressor. Failed.\n");
		return -1;
	}

	comp->compr_buf_size = 0;
	comp->compr_buf = NULL;
	comp->usecount = 0;
	comp->stat_compr_orig_size = 0;
	comp->stat_compr_new_size = 0;
	comp->stat_compr_blocks = 0;
	comp->stat_decompr_blocks = 0;
	D1(printk(KERN_DEBUG "Registering JFFS2 compressor \"%s\"\n", comp->name));

	spin_lock(&jffs2_compressor_list_lock);

	list_for_each_entry(this, &jffs2_compressor_list, list) {
		if(this->priority < comp->priority) {
			list_add(&comp->list, this->list.prev);
			goto out;
		}
	}
	list_add_tail(&comp->list, &jffs2_compressor_list);
out:
	D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
		printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
	})

	spin_unlock(&jffs2_compressor_list_lock);

	return 0;
}

int jffs2_unregister_compressor(struct jffs2_compressor* comp)
{
	D2(struct jffs2_compressor * this;)

	D1(printk(KERN_DEBUG "Unregistering JFFS2 compressor \"%s\"\n", comp->name));

	spin_lock(&jffs2_compressor_list_lock);

	if(comp->usecount) {
		spin_unlock(&jffs2_compressor_list_lock);
		printk(KERN_WARNING "JFFS2: Compressor modul is in use. Unregister failed.\n");
		return -1;
	}

	list_del(&comp->list);

	D2(list_for_each_entry(this, &jffs2_compressor_list, list) {
		printk(KERN_DEBUG "Compressor \"%s\", prio %d\n", this->name, this->priority);
	})
	spin_unlock(&jffs2_compressor_list_lock);
	return 0;
}

#ifdef CONFIG_JFFS2_PROC

#define JFFS2_STAT_BUF_SIZE 16000

char* jffs2_list_compressors(void)
{
	struct jffs2_compressor* this;
	char* buf, *act_buf;

	act_buf = buf = kmalloc(JFFS2_STAT_BUF_SIZE, GFP_KERNEL);
	list_for_each_entry(this, &jffs2_compressor_list, list) {
		act_buf += sprintf(act_buf, "%10s priority:%d ", this->name, this->priority);

		if((this->disabled) || (!this->compress))
			act_buf += sprintf(act_buf, "disabled");
		else
			act_buf += sprintf(act_buf, "enabled");

		act_buf += sprintf(act_buf, "\n");
	}
	return buf;
}

char* jffs2_stats(void)
{
	struct jffs2_compressor* this;
	char* buf, *act_buf;

	act_buf = buf = kmalloc(JFFS2_STAT_BUF_SIZE, GFP_KERNEL);

	act_buf += sprintf(act_buf, "JFFS2 compressor statistics:\n");
	act_buf += sprintf(act_buf, "%10s   ", "none");
	act_buf += sprintf(act_buf, "compr: %d blocks (%d)  decompr: %d blocks\n", none_stat_compr_blocks,
	                   none_stat_compr_size, none_stat_decompr_blocks);
	spin_lock(&jffs2_compressor_list_lock);
	list_for_each_entry(this, &jffs2_compressor_list, list) {
		act_buf += sprintf(act_buf, "%10s ", this->name);

		if((this->disabled) || (!this->compress))
			act_buf += sprintf(act_buf, "- ");
		else
			act_buf += sprintf(act_buf, "+ ");

		act_buf += sprintf(act_buf, "compr: %d blocks (%d/%d)  decompr: %d blocks ", this->stat_compr_blocks,
		                   this->stat_compr_new_size, this->stat_compr_orig_size,
		                   this->stat_decompr_blocks);
		act_buf += sprintf(act_buf, "\n");
	}
	spin_unlock(&jffs2_compressor_list_lock);

	return buf;
}

char* jffs2_get_compression_mode_name(void)
{
	switch(jffs2_compression_mode) {
		case JFFS2_COMPR_MODE_NONE:
			return "none";

		case JFFS2_COMPR_MODE_PRIORITY:
			return "priority";

		case JFFS2_COMPR_MODE_SIZE:
			return "size";
	}

	return "unkown";
}

int jffs2_set_compression_mode_name(const char* name)
{
	if(!strcmp("none", name)) {
		jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
		return 0;
	}

	if(!strcmp("priority", name)) {
		jffs2_compression_mode = JFFS2_COMPR_MODE_PRIORITY;
		return 0;
	}

	if(!strcmp("size", name)) {
		jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
		return 0;
	}

	return 1;
}

static int jffs2_compressor_Xable(const char* name, int disabled)
{
	struct jffs2_compressor* this;
	spin_lock(&jffs2_compressor_list_lock);
	list_for_each_entry(this, &jffs2_compressor_list, list) {
		if(!strcmp(this->name, name)) {
			this->disabled = disabled;
			spin_unlock(&jffs2_compressor_list_lock);
			return 0;
		}
	}
	spin_unlock(&jffs2_compressor_list_lock);
	printk(KERN_WARNING "JFFS2: compressor %s not found.\n", name);
	return 1;
}

int jffs2_enable_compressor_name(const char* name)
{
	return jffs2_compressor_Xable(name, 0);
}

int jffs2_disable_compressor_name(const char* name)
{
	return jffs2_compressor_Xable(name, 1);
}

int jffs2_set_compressor_priority(const char* name, int priority)
{
	struct jffs2_compressor* this, *comp;
	spin_lock(&jffs2_compressor_list_lock);
	list_for_each_entry(this, &jffs2_compressor_list, list) {
		if(!strcmp(this->name, name)) {
			this->priority = priority;
			comp = this;
			goto reinsert;
		}
	}
	spin_unlock(&jffs2_compressor_list_lock);
	printk(KERN_WARNING "JFFS2: compressor %s not found.\n", name);
	return 1;
reinsert:
	/* list is sorted in the order of priority, so if
	   we change it we have to reinsert it into the
	   good place */
	list_del(&comp->list);
	list_for_each_entry(this, &jffs2_compressor_list, list) {
		if(this->priority < comp->priority) {
			list_add(&comp->list, this->list.prev);
			spin_unlock(&jffs2_compressor_list_lock);
			return 0;
		}
	}
	list_add_tail(&comp->list, &jffs2_compressor_list);
	spin_unlock(&jffs2_compressor_list_lock);
	return 0;
}

#endif

void jffs2_free_comprbuf(unsigned char* comprbuf, unsigned char* orig)
{
	if(orig != comprbuf)
		kfree(comprbuf);
}

int jffs2_compressors_init(void)
{
	/* Registering compressors */
#ifdef CONFIG_JFFS2_ZLIB
	jffs2_zlib_init();
#endif
#ifdef CONFIG_JFFS2_RTIME
	jffs2_rtime_init();
#endif
#ifdef CONFIG_JFFS2_RUBIN
	jffs2_rubinmips_init();
	jffs2_dynrubin_init();
#endif
	/* Setting default compression mode */
#ifdef CONFIG_JFFS2_CMODE_NONE
	jffs2_compression_mode = JFFS2_COMPR_MODE_NONE;
	D1(printk(KERN_INFO "JFFS2: default compression mode: none\n");)
#else
#ifdef CONFIG_JFFS2_CMODE_SIZE
	jffs2_compression_mode = JFFS2_COMPR_MODE_SIZE;
	D1(printk(KERN_INFO "JFFS2: default compression mode: size\n");)
#else
	D1(printk(KERN_INFO "JFFS2: default compression mode: priority\n");)
#endif
#endif
	return 0;
}

int jffs2_compressors_exit(void)
{
	/* Unregistering compressors */
#ifdef CONFIG_JFFS2_RUBIN
	jffs2_dynrubin_exit();
	jffs2_rubinmips_exit();
#endif
#ifdef CONFIG_JFFS2_RTIME
	jffs2_rtime_exit();
#endif
#ifdef CONFIG_JFFS2_ZLIB
	jffs2_zlib_exit();
#endif
	return 0;
}
